The use of a CATV system to provide internet, voice over internet protocol (“VOIP”) telephone, television, security, and music services is well known in the art. In providing these services, a downstream bandwidth (i.e., radio frequency (“RF”) signals, and/or digital signals, optical signals) is passed from a supplier of the services to a user, and an upstream bandwidth (i.e., RF signals, digital signals, and/or optical signals) is passed from the user to the supplier. For much of the distance between the supplier and the user, the downstream bandwidth and the upstream bandwidth make up a total bandwidth that is passed via a signal transmission line, such as a coaxial cable. The downstream bandwidth is, for example, signals that are relatively higher frequencies within a total bandwidth of the CATV system, while the upstream bandwidth is, for example, signals that are relatively lower frequencies.
Traditionally, the CATV system includes a head end facility, where the downstream bandwidth is initiated into a main CATV distribution system, which typically includes a plurality of trunk lines, each serving at least one local distribution network. In turn, the downstream bandwidth is passed to a relatively small number (e.g., approximately 100 to 500) of users associated with a particular local distribution network. Devices, such as high-pass filters, are positioned at various points within the CATV system to ensure the orderly flow of the downstream bandwidth from the head end facility, through the trunk lines, through the local distribution networks, and ultimately to the users.
In contrast to the orderly flow of the downstream bandwidth, the upstream bandwidth passing through each of the local distribution networks is a compilation of an upstream bandwidth generated within a premise of each user that is connected to the particular local distribution network. The upstream bandwidth generated within each premise includes desirable upstream information signals from a modem and/or a set-top-box, and undesirable interference signals, such as noise or other spurious signals. Many generators of such undesirable interference signals are electrical devices that inadvertently generate electrical signals as a result of their operation. These devices include vacuum cleaners, electric motors, household transformers, welders, and many other household electrical devices. Many other generators of such undesirable interference signals include devices that intentionally to create RF signals as part of their operation. These devices include wireless home telephones, cellular telephones, wireless internet devices, CB radios, personal communication devices, etc. While the RF signals generated by these latter devices are desirable for their intended purposes, these signals will conflict with the desirable upstream information signals if they are allowed to enter the CATV system.
Undesirable interference signals, whether they are inadvertently generated electrical signals or intentionally created RF signals, may be allowed to enter the CATV system, typically through an unterminated port, an improperly functioning device, a damaged coaxial cable, and/or a damaged splitter. As mentioned above, the downstream/upstream bandwidth is passed through coaxial cables for most of the distance between the user and the head end. This coaxial cable is intentionally shielded from undesirable interference signals by a conductive layer positioned radially outward from a center conductor and positioned coaxial with the center conductor. Similarly, devices connected to the coaxial cable typically provided shielding from undesirable interference signals. However, when there is no coaxial cable or no device connected to a port the center conductor is exposed to any undesirable interference signals and will function like a small antenna to gather those undesirable interference signals. Similarly, a coaxial cable or device having damaged or malfunctioning shielding may also gather undesirable interference signals.
In light of the forgoing, it should be clear that there is an inherent, system-wide flaw that leaves the upstream bandwidth open and easily impacted by any single user. For example, while the downstream bandwidth is constantly monitored and serviced by skilled network engineers, the upstream bandwidth is maintained by the user, who is without the skill or knowledge required to reduce the creation and passage of interference signals into the upstream bandwidth. This issue is further compounded by the number of users connected together within a particular local distribution network, especially knowing that one user can easily impact all of the other users.
One method for maintaining an overall high signal quality of the upstream bandwidth is to implement a device that amplifies the signal strength of a particular user's the upstream bandwidth. It is important to note, however, that the implementation of such an amplifier may not be advantageous where there is a significant amount of undesirable interference signals, because the desirable and undesirable signals are each amplified by the same amount. Accordingly, the overall signal quality of the upstream bandwidth is not likely increased when such an amplifier is implemented.
For at least the forgoing reasons, a need has been identified for a device that can increase the signal strength of the upstream bandwidth without unnecessarily amplifying undesirable interference signals.